Dolmen of as Mamas Nature · San Xoán de Río, Terra de Trives, Ourense Image of San Xoán de Río, not of the place itself. A megalithic tomb near the hamlet of Cambela whose orthostats were left exposed when the earth tumulus that covered them was lost, testimony to the first settlers of the Navea valley. Photo: Ramon.reboledo (CC BY-SA 4.0) What to see and do in San Xoán de Río